The average marks in Science subject of a class of 20 students is 68. If the marks of two students were misread as 48 and 65 of the actual marks 72 and 61 respectively, then what would be the correct average ?

[ A ] 68.5

[ B ] 69

[ C ] 69.5

[ D ] 70

[ E ] 66

Answer : Option
B

Explanation :

Difference of marks = 72 + 61 - 48 - 65 = 20 Correct average marks = 68 + $20 \over 20$ = 68 + 1 = 69